1. Field of the Invention
The present invention relates to an electric rotary machine (hereinafter referred to as xe2x80x9crotary machine,xe2x80x9d or occasionally xe2x80x9cmotorxe2x80x9d as appropriate), and more particularly to a radial gap type rotary machine comprising a stator armature with discrete salient poles.
2. Description of the Related Art
In a conventional rotary machine including a stator armature (hereinafter referred to as xe2x80x9carmaturexe2x80x9d as appropriate) structured such that a plurality of ring-shaped yoke pieces, which are made of a soft magnetic plate, such as a silicon steel plate, and which each have a plurality of pole tooth portions protruding radially, are stacked in the axial direction, since each of the ring-shaped yoke pieces is punched out integrally with the plurality of pole tooth portions as a single piece (the armature composed of the ring-shaped yoke pieces thus structured is hereinafter referred to as xe2x80x9cintegral armaturexe2x80x9d as appropriate), pole teeth each composed of a stack number of pole tooth portions are not partitioned structurally and therefore a resultant armature will have superior magnetic efficiency (low reluctance). However, in a small rotary machine, since a wire is usually wound directly on each of the pole teeth, the integral armature makes the winding operation troublesome, and makes it extremely troublesome when the rotary machine is of inner rotor type. As a result, the winding operation takes a long time, and the winding incurs unsatisfactory space factor as well. And, due to the flyer-winding involved in this case, the wire is subject to torsional stress during the winding operation, thereby failing to ensure reliability of the winding area.
Under the circumstances above described, a rare earth magnet having high energy product has been developed recently, and the structure of a rotary machine can be reviewed by means of magnetic circuit analysis using a computer. This works to enable a rotary machine with an armature of discrete salient pole structure (this armature is hereinafter referred to as xe2x80x9cdiscrete armaturexe2x80x9d as appropriate) to obtain requisite motor characteristics. The rotary machine with the discrete armature may give some undesired increase in reluctance but offers great advantages of easier winding operation and increased space factor of winding, which outweigh the disadvantageous increase in reluctance. From this, it is now realized that the rotary machine with the discrete armature produces higher performance and is manufactured less expensively on the whole, and there is a growing demand for the discrete armature.
One example of the discrete armature is manufactured such that pole tooth portions are dismembered off its main body portion of an integral armature, a wire is wound around each of the dismembered pole tooth portions thereby constituting each salient pole portion, and that the pole tooth portions each with a wire wound therearound (namely, the salient pole portions) are rejoined to the main body portion by laser-welding, or the like.
The armature thus structured and manufactured, however, has a disadvantage that the integral armature has to be first sectioned into the main body portion and the pole tooth portions and later the sectioned portions have to be put back together, thereby requiring an additional time. Also, when the pole tooth portions each with a winding (salient poles) are rejoined to the main body portion, the stack layers of the both portions have to be matched with each other, and therefore it is required that respective portions be held together by a well-maintained tool and surely welded plate by plate for ensuring precision, which results in decreased workability. And, joints (welded portions) deteriorate significantly in mechanical strength and magnetic characteristics.
To overcome the above described problems, the present inventors disclosed in Japanese Patent Application Laid-open No. 2001-238377 a radial gap type rotary machine, in which a stator armature comprises: a plurality of discrete salient poles; a cylindrical pole tooth ring for positioning and magnetically and mechanically connecting the salient poles to one another; and a cylindrical stator ring adapted to house the salient poles and to decrease leakage flux resulting from magnetic discontinuity.
In the above described rotary machine, a molding resin is injected inside the stator ring, which can fix integrally the components constituting the armature, and at the same time can form a cylindrical space for housing a rotor with an accuracy as high as corresponding to that of an injection molding die employed.
The rotary machine, however, has a problem in that the molding resin, when injected, can harm connections between stator coil wire terminations and coil terminal pins, and also damage solder applied to the connections such that when the molding resin melted is injected inside the stator ring, the solder is melted due to the heat (about 200 degrees Centigrade) and flow of the resin, whereby problems such as a loose contact are caused, and in an extreme case the wires are broken or the melted solder flows to the salient poles or other electrodes resulting in electrical troubles.
The present invention has been made in view of the above problem, and it is an object of the invention to provide a rotary machine, in which a stator armature is structured such that the connections of the coil wire terminations with the coil terminal pins, and the solders applied to the connections are kept free from harm or damage when the molding resin is injected into the stator ring.
In order to achieve the above object, according to a first aspect of the present invention, a rotary machine includes a stator armature which comprises: a stator ring; a plurality of discrete salient poles each including a pole tooth and a coil, disposed inside the stator ring, and fixed by a molding resin injected inside the stator ring from an injection port of a molding die; and a plurality of barrier walls. Each of the barrier walls is disposed between the injection port of the molding die and two coil terminal pins to which the coil has its both wire terminations connected respectively.
According to a second aspect of the present invention, in the rotary machine of the first aspect, the both wire terminations of the coil are soldered to the two coil terminal pins.
According to a third aspect of the present invention, in the rotary machine of the first or second aspect, the barrier walls are provided on a terminal holder including a plurality of holes adapted to have the terminal pins inserted thereinto.
According to a fourth aspect of the present invention, in the rotary machine of the third aspect, the terminal holder is formed of resin.
Thus, in the rotary machine of the present invention, the barrier walls are each positioned between the injection port of the molding die and the connections of the coil wire terminations with the two coil terminal pins, and the solders applied to the connections, whereby the barrier walls prevent the injected molding resin from running directly against the connections and the solders. Accordingly, the connections and the solders do not directly receive physical and thermal impact of the molding resin flowing in, whereby the resin can be injected inside the stator ring without detriment to the connections and the solders.